It is well known to provide in jet aircraft an auxiliary system to produce both conditioned air to the cabin compartment for passenger comfort and refrigerated air for avionics cooling. Heretofore, cooling requirements for avionics and other components have been relatively modest. However, emerging low temperature technologies in, for example, super conductivity and magnetic bearings are presenting potentially beneficial applications in jet aircraft, assuming sufficient quantities of refrigerated air can be produced to create requisite low temperature operating environments. Since the air will have to be cooled to lower temperatures, well below 0.degree. F., the potential for icing increases dramatically. If the ambient input air to a refrigeration system contains any moisture, freezing will result, and ice will accrete to surfaces of system components. Refrigeration system performance is thus degraded.
The typical anti-icing approach is to remove moisture from the input air. Thus, cold air producing systems are equipped with separators which act to centrifuge water from the chilled air before freezing can occur. This approach requires additional flowpath volume in order to provide sufficient residence time to condense and centrifuge substantially all of the moisture from the air. Moreover, to provide effective separator operation, the chilled air temperature must be held within a relatively narrow band, which is difficult to achieve considering the wide range of flight conditions and power settings typically encountered in jet aircraft applications. Moreover, a moisture separator requires additional space and typically a reconfiguration of the refrigeration system to accommodate its inclusion at the appropriate location in the system.
Commonly assigned Renninger et al. U.S. Pat. No. 5,036,678 discloses a jet aircraft auxiliary refrigerated air system capable of cooling input air at a typical temperature of 1150.degree. F. down to a temperature well below freezing for environmental control purposes. However, this patent does not address the problem of icing.